This invention relates to a method for building up pregnane side chains in steroids. Reported methods, e.g., those reported in J. Amer. Chem. Soc., vol. 89 (1967): 5505, and J. Org. Chem., vol. 33 (1968): 3294, are useless for commercial scale manufacture of pregnane derivatives, both because too many reaction steps are required to build up the pregnane side chain and because individual reaction steps are too expensive for a commercially feasible process.
A process for the preparation of 17.alpha.-acyloxy- and/or 17.alpha.-alkoxy-20-ketopregnane derivatives from 17.alpha.-ethynylgonane-17.beta.-sulfite esters using mercury salts is recited in DOS's (German Unexamined Laid-Open Applications) U.S. Pat. No. 2,023,122, now U.S. Pat. Nos. 3,741,997; and 2,140,291 and 2,230,286, both now U.S. Pat. No. 3,764,615, both incorporated herein by reference.
However, this process is readily usable only on a laboratory scale, because of limitations on the yields attainable.